Quantum Time Reversed: Scientists Learn to Turn Back the Arrow of Time

In the quantum world, the laws of physics are largely symmetric with respect to time: the equations work the same whether time moves forward or backward. However, in reality we observe a clear “arrow of time” — processes unfold in one direction.

The researchers developed special control protocols involving a carefully designed Hamiltonian (a sequence of fields and pulses) and feedback.

As a result, quantum trajectories can appear as if the system is evolving backward in time.

The work opens new possibilities for quantum computers, more efficient preparation of quantum states, and a fundamental understanding of time at the microscopic level. The next step is experimental implementation on superconducting qubits.

Sources:

1. Los Alamos National Laboratory. "Scientists make quantum time flow backward in stunning physics breakthrough." ScienceDaily (July 3, 2026).
2. García-Pintos L.P. et al. "Reshaping the Quantum Arrow of Time." Physical Review X (2026). DOI: 10.1103/l18s-9vmh.